The compressor section of a turbine engine can be housed within a compressor outer casing or shell. FIG. 1 generally shows a prior compressor shell 12 that includes an upper half shell 12a and a lower half shell 12b. The lower shell half 12b has two circumferential ends 13. Likewise, the upper shell half 12a has two circumferential ends 15. Each circumferential end 13 of the lower shell half 12b can be secured to a respective one of the circumferential ends 15 of the upper shell half 12a. The abutting ends 13, 15 form a joint 14, which is referred to as the horizontal joint 14 because of its substantially horizontal orientation when assembled.
FIG. 2 shows a compressor section 10 of a turbine engine. In this section, the compressor shell 12 encloses a rotor (not shown) on which multiple rows of airfoils or blades 16 are mounted. The rows of blades 16 alternate with the rows of stationary airfoils or vanes 18, which can be attached to and extend radially inward from the compressor shell 12. In some instances, the vanes 18 can be provided in the form of a diaphragm 20. Each diaphragm 20 can include inner and outer radial bands 22, 24, referred to as shrouds, with a plurality of vanes 18 circumferentially arrayed therebetween. The diaphragm 20 can be made of two semi-circular halves.
The compressor shell 12 can include a slot 26 extending circumferentially along its inner peripheral surface 28. The outer shroud 24, which can be configured with hooks 29, is received in the slot 26 so as to mount the diaphragm 20 on the shell 12. To facilitate installation, ample clearance can be provided between the outer shroud 24 and the slot 26, as generally shown in FIG. 3. However, such clearance allows more relative movement between the diaphragm 20 and the shell 12, which can occur when subjected to vibration and other forces, such as unsteady and steady aero/fluid loads, during compressor operation. Over time, this relative movement between the outer shroud 24 (particularly hooks 29) and the compressor shell 12 can lead to wearing of the interfacing surfaces of these parts. One area of particular concern is at or near the horizontal joint 14 because the largest relative motion occurs at the free ends of the diaphragm 20. Experience has shown that cracks can develop in the outer shroud 24 at or near the horizontal joint 14. Further, wearing of the hooks 29 and/or the compressor shell 12 can allow even greater movement of the diaphragm 20, which, in turn, can cause the inner shroud 22 and/or components attached thereto to rub against neighboring rotating components. Such rubbing can result in significant damage.
Thus, there is a need for a system that can minimize the play between the compressor diaphragm and the compressor shell and the resultant wear.